5150 fet french stuff

[Gabriel]

Hey people,

I find some 5150 peavey clone with fets, by a french dude:

http://www.fichier-pdf.fr/2010/04/13/08zhzj8/PDF%205150%20-%20V1.31.pdf

Is it any good? What are your opinion about this stuff?

[phatt]

Yes just search these posts and you will find a few members use Fet circuits with success.

There are pitfalls to these circuits and once you start cascading them all together like that then *Noise* can be a real pain. Also at only 9 Volts I doubt the chances of success.

Why don't you build it and let us know of the outcome,, could be a real monster.
Cheers Phil.

[joecool85]

I've heard of varying results from the FET emulating tube circuits.  Some say it's perfect, others say it isn't even close.  I've not played with one myself, but it seems like from the sound clips I've heard and the reading I've done that they make a good sounding circuit.  Maybe not "exactly like a tube", but good sounding for sure.

[Gabriel]

Yeah, I'm seriously considering build this one in 18v (i've heard some saying that higher the voltage, better the sound) just to see what this thing can do (or cannot do...)

I heard some mesa boogie dual rectifier 3channel fet version,it seems work somewhat fine...

Anyway,  I think it will be a challenge get it right and fine .

[rowdy_riemer]

The Dr. Boogie works quite well at 9V, but Mensur has a higher voltage version that perhaps works better. I think part of the reason some of these might sound different is that they are biased by using a trimpot for the drain resistor. I believe this will have an effect on the output impedance of each stage and effect the frequency response to some degree. I think it might be better to use trim pots for source resistors. In the case of the schematic for this JFETified 5150, it looks like the resistor values are fixed. This is ok, so long as you order several j201's and handpick the ones that bias well with these resistor values.